In this vid, geek goddess of all things awesome, Jeri Ellsworth, details how she made her own NMOS transistors using a a kiln, rust and stain remover, Emulsitone spin on dopant, wafer she scored on eBay, and some vinyl sign-making material.

Homebrew NMOS Transistor Step by Step – So Easy Even Jeri Can Do It

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Gareth Branwyn

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor for Boing Boing and WINK Books. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.


  • Bob A.

    “Roll your own” comes from cigarettes (tobacco or pot). Could we find a different metaphor for the title?

    • Gareth Branwyn

      I appreciate your sensitivity to this, Bob. And I will take it under advisement.

      While you’re right about the origins of that phrase, it has become widely adopted, in geekspeak and beyond, to refer to any homemade solution. The other common word, which Jeri used, is “homebrewed,” and again, it has traveled far beyond its original meaning of brewing beer. So, cigarettes or booze. But maybe I’ll choose “homemade” more in the future. That makes me think of things like cookies and pie. Something we can all feel good about!

      • Bob A.

        Interestingly, if you Google “roll your own”, the results are dominated by tobacco sellers. If you Google “homebrew”, you get a good number of techie results.

        So I would suggest that “homebrew” has wandered farther from its origins than “roll your own” has.

      • Brick Moon

        Transistors are gateway components. Stick to diodes, kids. Just say NP.

  • baz

    *Please please please*, if anyone attempts this definitely do your research on Hydrofluoric Acid (HF). All labs that use this substance require special training, and in my lab if someone is using HF he/she has to inform the other users of the lab, and if they haven’t had the training they’ve got to leave.

    It is one of the nastiest chemicals you’re likely to meet. If you spill some on your skin you won’t feel it immediately as it disrupts your nerves and passes down through your skin. It then reacts with the calcium in your blood which can cause cardiac arrest, and will eat away at your bones, and that’s when you start to get a burning feeling under your skin. By this time it’s already done you serious damage, and amputation may be necessary.

    I’m not trying to be macabre or shock anyone, and I’m not taking away from this video, it’s brilliant; step-by-step instructions for real at-home science is awesome! I just want to impress upon you the nastiness that is HF.

    http://en.wikipedia.org/wiki/Hydrofluoric_acid

  • EngineerZero

    This is brilliant.

    By the way, the ‘Homebrew’ Computer Club was where Steve Jobs and Steve Wozniak met and started Apple Computer.

  • MadRat

    Sheesh, I can barely understand what to DO with a transistor let alone make one.

  • John

    I couldn’t believe it so I looked it up. Yes, you can go to the grocery store right now and buy a “rust stain remover” that is a solution of hydrofluoric acid. I couldn’t find the concentration anywhere, but the MSDS sheet is the stuff of nightmares. It must be pretty dilute, otherwise I can’t imagine how it could continue to be so easy to get.

    • klee27x

      I can’t believe we’ve come to the point where people are outraged that we are actually allowed to buy and sell useful things in a grocery store.

  • John Baichtal

    Badass. Now all the hackerspaces will run out and get hobbyist kilns!